Thanks for all the input everyone. Looks like I'll be looking for a Small 585 (so far they seem quite hard to come by). If anyone is selling one or comes across one reasonably please let me know. My XS is on craigslist and a few other forums I'll try and blow that there before I have to deal with ebay fee's. If anyone's interested in it send me an email, it's in great shape.
Does anyone know how a 51cm Cervelo R3 would fit compared to a Small 585? I'd rather have another 585 but the R3's are fairly easy to find
The original R3 woould have a significantly shorter reach, since the STA is 73 degrees and the LOOK has a 74.5 degree STA, that increases the reach (with the saddle in the same position, relative to the BB).
FWIW, I bought a 51cm R3 when it first came out and hated it. I only rode it for 200 miles before tearing it down and buying my first 585 in a size small (I've owned two). The current R3 has a different geometry, with longer chainstays and a more relaxed HTA that combine to make the wheelbase and front-center longer, much like a LOOK, but the reach should still be shorter.